Problem to be solved: Skin cancer is the most common of all cancers, accounting for nearly half of all reported cancer cases in the USA. According to the American Cancer Society (ACS), the best way to lower the risk of non-melanoma skin cancer is to practice sun safety by applying broad-spectrum sunscreens. One major disadvantage of commercial sunscreens is that the filters lack substantively with the skin and are easily removed by normal wear. As a consequence, the consumer must constantly reapply the sunscreen to benefit from the protection offered by the product. Product and Long-Term Goal: Nanometics has developed coated inorganic sunscreen filters that form temporary bonds with the epidermis, providing for long-wear protection from UV radiation. The filters are useful as ingredients in topical delivery systems and we anticipate that these filters will alleviae the need for constant product reapplication. The novel filters will be sold globally as powders and specialty dispersions, to be incorporated as long-wear ingredients in topical formulas. Technical Innovation: A naturally occurring anti-oxidant ligand, adsorbed to the surface of sunscreen grade TiO2 and ZnO particles, acts as a hetero bifunctional linker and forms temporary covalent bonds with epidermal amines, chemically linking the particles to the skin. Preliminary results have demonstrated that the novel particles exhibit water resistant properties. Thus far we have demonstrated the preliminary safety of these particles in a human clinical panel and their utility in an established in vitro skin model. Phase I Hypothesis: The Phase I hypothesis is that adsorption of the ligand onto the sunscreen filter does not negatively impact (1) the breadth and magnitude of UV protection and will not (2) increase the cytotoxicity or photogenotoxicity of the particles. Specific Aims: The specific aims of this Phase I SBIR are to (1) determine the particles breadth of UV protection in vitro and magnitude of UV protection in a human panel and (2) To determine the cytotoxic and photogenotoxic potential of the particles in vitro. Phase II: Phase II SBIR studies will focus on optimizing the long-wear attributes of the particles in vivo and demonstrating the complete toxicological profile of these particles in established models. Commercial Opportunity: The sun care market is estimated to represent 13.30% of the $9.7 billion domestic skin care market. As the public becomes more educated about the dangers of UV exposure, the sun care market is expected to grow more rapidly than other segments. Discussions with executives at cosmetic companies (Avon, Estee Lauder) indicate a need for long-wear sunscreen filters that are substantive on human skin. PUBLIC HEALTH RELEVANCE: Skin cancers, such as squamous and basal cell carcinomas, represent the most common form of cancer in the United States. Exposure to ultraviolet (UV) light is a known risk factor for the development of skin cancer and health care agencies recommend that topical sunscreens be used as preventative measures against UV exposure. This project seeks to advance the use of long-wear sunscreen filters that will protect the consumer from the harmful effects of radiation, without the need for constant reapplication.